The main components of a motor vehicle drivetrain are a drive motor and a transmission. A transmission converts torques and speeds and so transforms the traction force provided by the drive motor. The present invention concerns a method for the operation of a drivetrain which comprises at least a drive motor and an automatic transmission. In the context of the present invention, the term “automatic transmission” is understood to mean any transmission that effects automatic gear changes, these also being known as variable speed transmissions.
From DE 100 35 479 A1, a method for operating an automatic transmission is known in which successive upshifts and successive downshifts can be carried out with some overlap in order to improve the shift speed. For this, during each first upshift or downshift, a shift element needed for the subsequent second upshift or downshift is prepared, while the first upshift or downshift is in progress, in such manner that when a synchronization point is reached, namely a synchronous speed of the first upshift or downshift in progress, the subsequent second upshift or downshift can be carried out immediately.
In this way, according to DE 100 35 479 A1, single shifts are overlapped with one another, which means that each first upshift or downshift carried out and each subsequent second upshift or downshift is a single shift between two directly successive gears.
The method known from DE 100 35 479 A1 can be used for an automatic transmission with five shift elements of which, two shift elements are engaged for transmitting torque and/or transmitting power in one forward gear and one reverse gear and three shift elements are disengaged. Such an automatic transmission can be used to implement six forward gears. In the development of automatic transmissions, a trend toward an ever-greater number of gears, particularly for the forward gears of an automatic transmission, can be observed. Presently, for example, automatic transmissions with eight forward gears and one reverse gear are under development, wherein such automatic transmissions have at least five shift elements such that, for torque or force transfer at least five shift elements are disengaged in one forward gear and one reverse gear and the remaining shift elements are engaged. The method known from DE 100 35 479 A1 is not suited for such an automatic transmission.
Starting from this, the present invention addresses the problem of providing a new type of method for the operation of a drivetrain comprising at least an automatic transmission and a drive motor.